I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Andreas: if I don't get a solution here, is this something I should open as a support request. It will be an RFE otherwise.

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Doug,

if I'm getting you right (upon rereading), you want the connection protocol to

• determine whether what you're connecting to is a primary (or standard) and
• if not (it's a secondary), to tell the client who the primary is and
• possibly how/where to reach that

This is not even what you'd get from sqlhosts group connects  (they'd simply walk all the group members until they get connected, no matter the cluster role).

In fact this is one of the CM's core functionalities, and I don't think this can/should be packed into the connection protocol, neither SQLI nor DRDA.

Sorry for not seeing it this way in my previous post, and let me know if I'm again missing anything.

Have a nice weekend!

 Andreas

Andreas: if I don't get a solution here, is this something I should open as a support request. It will be an RFE otherwise.

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Andreas.

Not so! We have used groups that way as long as I can remember. For example:

https://www.ibm.com/docs/en/informix-servers/14.10.0?topic=cshac-properties-connecting-high-availability-cluster-servers-through-sqlhost-file-group-entries

It's the same for other APIs that use "sqlhosts" or equivalent Windows registry constructions, though I can only find a clear statement for JDBC as above.

Will post a proof of that with "dbaccess" next time I have a test cluster running.

Hi Doug,

if I'm getting you right (upon rereading), you want the connection protocol to

• determine whether what you're connecting to is a primary (or standard) and
• if not (it's a secondary), to tell the client who the primary is and
• possibly how/where to reach that

This is not even what you'd get from sqlhosts group connects  (they'd simply walk all the group members until they get connected, no matter the cluster role).

In fact this is one of the CM's core functionalities, and I don't think this can/should be packed into the connection protocol, neither SQLI nor DRDA.

Sorry for not seeing it this way in my previous post, and let me know if I'm again missing anything.

Have a nice weekend!

 Andreas

Andreas: if I don't get a solution here, is this something I should open as a support request. It will be an RFE otherwise.

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Andreas:

Doug is correct. Using an sqlhosts group that includes both primary and secondary servers, a connection to the group name will preferentially connect to a primary over secondaries even if the secondaries are listed earlier in the group within the sqlhosts file. It has always worked that way for native SQLI connections.

Art

Hi Andreas.

Not so! We have used groups that way as long as I can remember. For example:

https://www.ibm.com/docs/en/informix-servers/14.10.0?topic=cshac-properties-connecting-high-availability-cluster-servers-through-sqlhost-file-group-entries

It's the same for other APIs that use "sqlhosts" or equivalent Windows registry constructions, though I can only find a clear statement for JDBC as above.

Will post a proof of that with "dbaccess" next time I have a test cluster running.

Hi Doug,

if I'm getting you right (upon rereading), you want the connection protocol to

• determine whether what you're connecting to is a primary (or standard) and
• if not (it's a secondary), to tell the client who the primary is and
• possibly how/where to reach that

This is not even what you'd get from sqlhosts group connects  (they'd simply walk all the group members until they get connected, no matter the cluster role).

In fact this is one of the CM's core functionalities, and I don't think this can/should be packed into the connection protocol, neither SQLI nor DRDA.

Sorry for not seeing it this way in my previous post, and let me know if I'm again missing anything.

Have a nice weekend!

 Andreas

Andreas: if I don't get a solution here, is this something I should open as a support request. It will be an RFE otherwise.

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

You're both correct, and I stand corrected.

So this is baked into the SQLI protocol which, of course, we fully own and have control over and which we equipped to our user's needs our db server's (cluster) capabilities.

The same cannot be told about DRDA. And I couldn't quickly find any clue online that DRDA would support any such role based connection preference. I'm afraid this would already fail at the fact that, with DRDA, you'd first have to reach a server to obtain any information about alternate servers (among which the client then could pick based on role would that be implemented).
Alternatively, from what I'm getting from some (Db2 HADR) place is the idea there is to use a virtual IP address which some (HADR manager?) entity then has to (re-)assign to the host hosting the current HADR primary server.

BR,
 Andreas

Andreas:

Doug is correct. Using an sqlhosts group that includes both primary and secondary servers, a connection to the group name will preferentially connect to a primary over secondaries even if the secondaries are listed earlier in the group within the sqlhosts file. It has always worked that way for native SQLI connections.

Art

Hi Andreas.

Not so! We have used groups that way as long as I can remember. For example:

https://www.ibm.com/docs/en/informix-servers/14.10.0?topic=cshac-properties-connecting-high-availability-cluster-servers-through-sqlhost-file-group-entries

It's the same for other APIs that use "sqlhosts" or equivalent Windows registry constructions, though I can only find a clear statement for JDBC as above.

Will post a proof of that with "dbaccess" next time I have a test cluster running.

Hi Doug,

if I'm getting you right (upon rereading), you want the connection protocol to

• determine whether what you're connecting to is a primary (or standard) and
• if not (it's a secondary), to tell the client who the primary is and
• possibly how/where to reach that

This is not even what you'd get from sqlhosts group connects  (they'd simply walk all the group members until they get connected, no matter the cluster role).

In fact this is one of the CM's core functionalities, and I don't think this can/should be packed into the connection protocol, neither SQLI nor DRDA.

Sorry for not seeing it this way in my previous post, and let me know if I'm again missing anything.

Have a nice weekend!

 Andreas

Andreas: if I don't get a solution here, is this something I should open as a support request. It will be an RFE otherwise.

Hi Andreas.

Indeed. I was able to get that working with a Connection Manager on each IDS server as follows:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><configuration>  <!--    C:\ProgramData\IBM\DB2\IBMDBCL1\cfg\db2dsdriver.cfg    Informix cluster IBM Data Server Driver prototype configuration file    Doug Lawry, Oninit Consulting, January 2026    Routes to Informix Connection Manager (CM) on either of two Informix hosts.    Informix Dynamic Server (IDS) instances also run on each of those same hosts.    High-availability Data Replication (HDR) maintains a passive read-only replica.    Server 1 is usually the primary IDS instance and therefore more heavily loaded.    Server 2 is therefore the preferred CM, so use DSN "alias2" in applications.    Test with: testconn40 "database=alias2;userid=...;password=..."  -->  <dsncollection>    <dsn alias="alias1" name="dbname" host="host1" port="9089"/>    <dsn alias="alias2" name="dbname" host="host2" port="9089"/>  </dsncollection>  <databases>    <database name="dbname" host="host1" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias2" hostname="host2" port="9089"/>        </alternateserverlist>      </acr>    </database>    <database name="dbname" host="host2" port="9089">      <acr>        <!-- Automatic client reroute -->        <parameter name="enableAlternateServerListFirstConnect" value="true"/>        <alternateserverlist>          <server name="alias1" hostname="host1" port="9089"/>        </alternateserverlist>      </acr>    </database>  </databases></configuration>

But I can't find a way above to make it connect to whichever is the primary IDS server in an alternate server list so that we don't need Connection Managers at all, as with an sqlhosts group for standard TCP listeners.

Hi Doug,

I vaguely remember having dealt with this, my notes having things like alternateserverlist and enableAlternateServerListFirstConnect
and a pointer to https://www.ibm.com/docs/en/db2/11.5.x?topic=njcshads-non-java-client-support-high-availability-connections-informix-servers

Basically, I think what you're looking for is part of the DRDA protocol, so needs to be configured on that level (outside of onconfig, and outside of sqlhosts anyway).

HTH,
 Andreas

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Gerd.

Thanks, but the purpose of this thread is to get automated HDR fail-over redirection working without Connection Manager.

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Doug:

I don't know, but does the DRDA driver obey using sqlhosts groups? They can be used for failover and default to using the primary or the first listed group member if all are peers.

Art

Hi Gerd.

Thanks, but the purpose of this thread is to get automated HDR fail-over redirection working without Connection Manager.

I was recently unable to work out how to do this directly on latest IDS 14.10. I am about to write a technical article on a work-around using Connection Manager, but that involves more effort and failure points. Does anyone know how to construct a DRDA client configuration so that it connects to whichever is the primary in an HDR pair like you can in "sqlhosts" for native TCP connections?

Hi Gerd. Could you share your connection string to CM? I'm trying to connect via JDBC (ifxjdbc.jar).

Thanks,